The need for direction finding in connection with the Target Identification and Acquisition System (TIAS) project brought about investigations into the possibilities of using a time of arrival (TOA) technique. The requirements were that the system must be capable of direction finding (DFing) on a single pulse, have a look angle of 120.degree. (i.e. 60.degree. on each side of bore sight) and have an angle resolution in tenths of a degree. Such systems must be insensitive to pulse rate frequency (PRF) up to 5 KHz, emitter pulse height, emitter pulse width, emitter pulse rise time and carrier frequency.
The system requires the measurement of the time difference occurring between the incidence of electromagnetic energy as it strikes different receivers, e.g. the antennas in the wing tips of an aircraft. Although the system is described herein as applied to direction finding for TIAS, other applications for this short time, monopulse TOA system are possible, for example, in ultra short range radar for extreme low level missile guidance systems, precise ELINT adaptions in connection with direction finding of enemy emitters, aximuth bearing rate calculations, bench instrumentation for single occurrence, short time delays (pico second resolution), and locators for sonobouys in connection with ASW work.
Other applications will undoubtedly be suggested to workers in the field for the devices as described in the following specification.